ELECTRODEPOSITED ANTIMONY AND ANTIMONY TELLURIDE AS BACK CONTACT INTERLAYER FOR CADMIUM TELLURIDE THIN FILM SOLAR CELLS

摘要

Electrodeposition is chosen for preparation of the back contact for CdS/CdTe thin film solar cells because it is one of the most inexpensive ways to form thin films. Common CdTe solar cells have the following superstrate configuration: TCO/CdS/CdTe/metal. The CdTe-metal back contact is one reason for losses in the fill factor and the efficiency. This is caused by the high electron affinity of CdTe and the difficulty to get p~(++)-CdTe. The stability of the contact could be reduced by diffusion of metal atoms from the back contact or by the formation of the metal telluride in the Te rich surface. Both problems are supposed to be solved by deposition of an intermediate layer between CdTe and the metal back contact. Electrodeposited Sb and Sb_2Te_3 should act as a diffusion barrier and may improve the ohmic contact due to p-doping the CdTe surface. The parameters of the Sb_2Te_3 and Sb electrodeposition have been varied. In order to find the correct parameters SbO~+/Sb and HTeO_2~+/Te redox systems are studied by means of cyclic voltammetry on ITO-sub-strates. These Sb and Sb_2Te_3 layers deposited on ITO-substrates are characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and x-ray diffraction (XRD). An accelerated life time test has been done for solar cells at 373 K and 1 sun.